Currently, the digestive tract infections are caused by pathogenic and opportunistic microorganisms. As an example, we mention the toxigenic strains of Escherichia coli (ETEC) which produce enterotoxins that cause diarrhea and dehydration both in humans, known as traveler's diarrhea, and in animals, called colibacillosis.
In humans, ETEC is the most common cause of traveler's diarrhea, which affects millions of visitors in tropical and subtropical risk areas every year. These pathogens can be acquired by ingesting contaminated food and water. In the veterinary sector, the production of pork is successful chain in Brazilian agribusiness. The enteric colibacillosis is the disease with the highest Impact on the pig farming industry, not limited to it. Therefore, it is still common to use chemical additives in feed as growth promoters. However, therapeutic and prophylactic products may leave residues in edible products, contaminate the ecosystem and develop resistant microbial strains.
Given these problems, some government agencies in several countries have been limiting the use of antimicrobials, in addition to banning them as animal growth promoters, which are demanding the search for alternatives to the use of these substances.
Among the viable alternatives for the replacement of antimicrobials as growth promoters are the development and application of vaccines, control of environmental conditions for the creation, and use of feed (diet) with the appropriate use of prebiotics, probiotics, synbiotics, enzymes and compounds of vegetables.
The work of Hur and Lee (2012) compares the effects of a vaccine candidate against ETEC to the obtained by a commercial vaccine, revealing that the candidate developed by the research group is promising in fighting the coli bacillosis. However, the preparation of the vaccine involves the study of genes that cause ETEC virulence, the insertion of these genes into a plasmid and the transfection of plasmids into an attenuated microorganism and then for the animals immunization. The microparticle proposed in the present invention dispenses the use of genetic engineering techniques that, in addition to make the product more expensive, also presents efficacy, safety and ethical and social aspects as barriers to marketing.
Additives to food to replace antibiotic has been proposed and shown to be effective in combating ETEC. The work of Wu at al. (2012) shows that the peptide cecropin AD added to the basal diet in a proportion of 400 mg/kg have efficacy in increasing immunity and retention of nitrogen and energy, as well as the reduction of intestinal pathogens in weaned piglets. However, cecropin AD used in this work was obtained by isolation of Hyalophora cecropia and its expression in genetically modified microorganism Bacillus subtilis, a process that requires the purification of the used substance and whose practical results of applying the diarrhea control in porcines was found to be intermediate to the control group and the group treated with antimicrobials (kitasamycin 100 mg/kg and colistin sulfate 800 mg/kg). The microparticle proposed in the present invention showed to have similar activity to antibiotics and to be superior to the used control.
The document CN102178115 dated May 13, 2011, relates to a composition comprising different corn-, soybean-, calcium- and fish-derived products for addition to food (premix) of weaned piglets. The alleged advantage for the final composition (premix reinforced with corn-, soy-, calcium- and fish-derived products) is to solve problems of immune failure, secretion of digestive enzymes, low development of the digestive tract and frequent diarrhea in these animals. However, there is no part of the composition containing vitamins, minerals and enzymes that acts directly on ETEC or other pathogenic microorganisms.
In humans, the work of Hayat et al. (2011) shows that the current practice in the travelers diarrhea control is present in education, aggressive fluid replacement, antidiarrheal therapy, and the use of antimicrobials. However, there is concern about the irrational use of antimicrobials due to induction of bacterial resistance. Alternatively, there is evidence that a form of control of infections of the digestive tract, according to Licht et al. (2012), is the use of probiotics capable of selectively stimulate the growth of intestinal beneficial bacteria in the colon. However, the absence of publications with negative results may represent a bias in confirming the use of prebiotics as a method of controlling or preventing these infections.
Patent US20030157159, dated Aug. 21, 2003, describes a composition containing terpenes and a surfactant in the ratio of 1 to 99%, which are useful for the prevention or treatment of infections of the digestive tract in animals and humans. It also proposes the inclusion of the referred terpenes in liposomes. However, the in vitro antimicrobial activity to various pathogens reported in this document is demonstrated by the mixture of terpenes not included in liposomes, which serve to stabilize the mixture to actual use. The microparticles of the present invention are obtained by microencapsulation of Cymbopogon citratus and Cymbopogon martinii oils with soluble walls, which gives better product solubility in water due to the fact that rely on a process to obtain an emulsion and contain a surfactant as an auxiliary. As it is originally an oil, this is an advantage in terms of absorption in the animal, since the use is oral.
The work of Li et al. (2012), as well as the document WO2008/155536, dated Jun. 18, 2007, relates to a supplement for feeding piglets with the present invention micro-encapsulated essential oils, mainly containing cinnamaldehyde, which is able to increase food intake, rate growth and diarrhea incidence in animals, but it is a compound relatively toxic and allergenic (Junior et al., 2005). The present invention, however, proposes a microparticle containing micro encapsulated Cymbopogon citratus and Cymbopogon martinii essential oils, whose antimicrobial activity, when in combination, is greater than the activity of the two oils isolated. Such microparticle presents safe use and demonstrates in vitro antimicrobial effect and satisfactory performance when used in the feed of porcines in the nursery phase, with potential use in replacement to antibiotics used as growth promoters in animals and as a gastrointestinal infections prophylactic microparticle in humans.
In view of the prior art, the present invention has advantages in several aspects. First, the technique of microencapsulation by spray-dryer is a well-established industrial technique easily implemented from laboratory scale to the industrial scale. Microencapsulation provides a product stable to external agents such as oxygen and light, especially during the product storage.
The present invention is applicable in the pharmaceutical and veterinary fields for the prevention of gastrointestinal infections caused by enterobacteria such as Escherichia coli ETEC, especially as a growth promoter in the feed of porcines.